progshot

progshot is a debugging tool that enables "offline-debugging" for your python program.

Install

pip install progshot

Usage

Trace

To capture a continuous run and be able to offline debug it like a real debugger, use @trace

from progshot import trace

def swap(arr, i, j):
    arr[i], arr[j] = arr[j], arr[i]

@trace
def bubble_sort(arr):
    n = len(arr)
    for i in range(n - 1):
        for j in range(n - i - 1):
            if arr[j] > arr[j + 1]:
                swap(arr, j, j + 1)

@trace will record every line executed in the decorated function and generated a out.pshot file when the program exits. With psviewer, you can enjoy a debugger-like environment offline, where you can not only go forward, but go backward as well.

Each capture is called a film, which contains all the frames the local variables in them.

from progshot import trace

def swap(arr, i, j):
    # Now this function will be recorded as well
    arr[i], arr[j] = arr[j], arr[i]

@trace(depth=2)
def bubble_sort(arr):
    n = len(arr)
    for i in range(n - 1):
        for j in range(n - i - 1):
            if arr[j] > arr[j + 1]:
                swap(arr, j, j + 1)

from progshot import dump

for i in range(3):
    arr = [random.randint(0, 100) for _ in range(10)]
    bubble_sort(arr)
    dump(filename=f"sort_{i}.pshot")

View

To view the report, you can use Web interface or CLI.

Web

psview out.pshot

CLI

psview-cli out.pshot

Web interface also provides a terminal which behaves like the CLI.

The CLI interface is similar to pdb. You can use commands that have the similar meanings in pdb, except that you have a set of "backward debugging" commands.

Single Capture

You can also use capture function to do a single capture.

from progshot import capture

def add(a, b):
    capture()
    return a + b

from progshot import capture

def add(a, b):
    capture(name="cap_in_add")
    return a + b

Config

There are some global configs that you can change through config.

from progshot import config

# Change the default dump file name
config(filename="other.pshot")

# Do not auto-save when the program exits
config(save_at_exit=False)

# Change default trace depth to 10
config(depth=10)

Bugs/Requests

Please send bug reports and feature requests through github issue tracker.

License

Copyright Tian Gao, Mengjia Zhao, 2021.

Distributed under the terms of the Apache 2.0 license.